the 30-06 has a wee bit more capacity
you can get some awsome brass from Lapua and its almost never
"out of stock" here in the US where the 6.5-284 is quite often.
the 6.5-06 will feed better from the mag box with less fuss.

but the 6.5-284 chambered in a long action will allow you to seat the bullets out as far as you want with no trouble feeding from the mag
the 6.5-284 has a wining reputation with alot of differant shooting sports

Ballisticaly an animal will never tell the differance and more than likely neither will you , the accuray nitch for the heavy 6.5 bullets seems to be in the 2800-3000fps range thats done very easly with the 06 case where you may be pushing the 284 a little bit more to get to 3000fps either way you will likely be rnning them at very close to the same speeds so again their is no real ballisitic advantage

if you ever plan to sell the gun the 6.5-284 will probably get you a sell faster than the less common 6.5-06

I actually checked that the other day with imr 4350 the 6.5x284 norma cases, norma brand, and the 30-06 with winchester cases, to my surprise they both held exactlly 66.2 grns to the top of the neck. And it is not hard to push a 140 at 3000fps with 26" or more barrel. mine has a 30" pipe and when I first started testing I was hitting 3160-3180fps with 139 lapuas but at those speeds it leaves you with vertical stringing. oh and the reason most manuals show the 6.5-06 with the advantage is because they show the 6.5x284 loaded at 2.990" or shorter to fit a short action.

I actually checked that the other day with imr 4350 the 6.5x284 norma cases, norma brand, and the 30-06 with winchester cases, to my surprise they both held exactlly 66.2 grns to the top of the neck. And it is not hard to push a 140 at 3000fps with 26" or more barrel. mine has a 30" pipe and when I first started testing I was hitting 3160-3180fps with 139 lapuas but at those speeds it leaves you with vertical stringing. oh and the reason most manuals show the 6.5-06 with the advantage is because they show the 6.5x284 loaded at 2.990" or shorter to fit a short action.

the .284 case works just fine with a 24" barrel just like the 06 case. The verticle stringing is probably from barrel harmonics with the long 30" barrel. I doubt you'd see 50 fps difference with a 26" barrel, but most of the stringing would go away. The 6.5-06 packed with 3100 will show about 3250fps without reaching the 57 grains max powder weight.
gary

The barrel is 30" 1.120" to 1.055" taper it was'nt the barrel lenght, I was getting those speeds with 51.5 grns Imr 4350 with CCI 200s, and 3.133" oal, I am now down to 49.1 grns Imr 4350, CCI BR-2s, 3.133" oal case necks turned and polished on the inside, and dropped to a .291" bushing, it averages 3020fps with a 7 ES, it was a inconsistent neck tension issue, but your right it can be done in a 26" pipe, or come pretty close with a 24".